1. Field of the Invention
This invention relates to power tongs and, in one aspect, to power tongs for releasing tight joints and to a bucking unit including such tongs.
2. Description of Related Art
Tongs are used for connecting and disconnecting threaded members. Generally, they are used in pairs, one tong (known as a "back-up tong") holding one length of pipe fast and the other tong (referred to herein as a "power tong") rotating a second length of pipe with respect to the first.
Typical power tongs have a rotary with pipe gripping jaws that is rotatably mounted in a housing and is driven in rotation by a gear train powered by an hydraulic motor. The hydraulic motor is usually capable of tightening joints to the required torque, but problems can arise when trying to separate pipes, for example, the pipes of a drill string that has been withdrawn from a bore.